Abstract
Various 5′-0-N-protected deoxynucleoside-3′-0-β-cyanoethyl-N,N-dialkylamino-/N-morpholinophosphoramidites were prepared from β-cyanoethyl monochlorophosphoramidites of N,N-dimethylamine, N,N-diisopropylamine and N-morpholine. These active deoxynucleoside phosphites have successfully been used for oligodeoxy-nucleotide synthessis on controlled pore glass as polymer support and are very suitable for automated DNA-synthesis due to their stability in solution. The intermediate dichloro-β-cyanoethoxy-phosphine can easily be prepared free from any PCl3 contamination. The active monomers obtained from β-cyanoethyl monochloro N,N-diisopropylaminophosphoramidites are favoured. Cleavage of the oligonucleotide chain from the polymer support, N-deacylation and deprotection of β-cyanoethyl group from the phosphate triester moiety can be performed in one step with concentrated aqueous ammonia. Mixed oligodeoxynucleotides are characterized by the sequencing method of Maxam and Gilbert.